1. Field of the Invention
The present invention relates to a vehicle door structure, and in particular to a vehicle door structure configured with a door outer panel disposed at the outside of a door and a door inner panel disposed at the inside of the door.
2. Description of the Related Art
Vehicle door structures are known, such as described in Japanese Patent Application (JP-A) Nos. 2004-314696, 2003-252057, and 2004-26070. In JP-A No. 2004-314696 an example of a vehicle door is described, with the door provided with main structures of a door body and an outer panel. The door body is formed as a substantially rectangular frame (skeleton structure), and the outer panel is fixed to the door body on the vehicle outside. Furthermore, the door as a whole, provided with the door body and the outer panel, is preferably configured from a light alloy, such as an aluminum alloy, magnesium alloy or the like.
However, when the door is configured as a whole from such a light alloy that has a large linear expansion coefficient, such as aluminum alloy, magnesium alloy or the like, and, furthermore, the door as a whole is placed, for example, in a high temperature environment (such as a bake oven in electrophoretic coating), there is thermal expansion of the door as a whole. At such a time, the thermal expansion amount of the outer panel, since it is formed as a single sheet, is greater than that of the door body. Therefore, in such a door, a difference is generated in the thermal expansion conditions between the door body side and the outer panel side. There is a possibility of permanent deformation being generated, due to thermal distortion at the outer sheet portion of the door that is provided at the outer panel side, caused by the difference in the thermal expansion conditions between the door body side and the door panel side.
The present invention is made in consideration of the above circumstances and provides a vehicle door structure that may suppress permanent deformation of the door.